Tissues Flashcards
What is a membrane?
It is the envelop of an organ that is thin and “fluid”.
Of what is composed the membrane structure?
Of a bilayer phospholipids, of sterol lipids and proteins.
What is the composition of the phospholipids?
They have a hydrophobic tail and a hydrophilic head.
Why to the phospholipids form a bilayer?
Because the hydrophobic tails repeal water and the hydrophilic heads are attracted to water. Since the cells are mostly in aquous solution, the tails tend to regroup together and the head tend to attach to the water molecules.
What kinetic do the phospholipid have?
They are in constant movement in the same plane.
How are called the sterol lipids in animals and in plants?
They are cholesterol in animal cells and phytosterol in plants.
What is the purpose of sterol lipids?
They stabilize the membrane. The sterol lipids fit between the fatty acid chain and keep a certain fluidity to the chain.
In with digestional juice are sterol lipids important?
They are important in the synthesis of the bile.
What is the purpose of proteins in the cell membrane?
They make the channels.
What are the different types of proteins on the membrane cell?
- integral membrane protein
- trnasmembrane proteins (lactose permease)
- Peripheral membrane
In order from the smallest to the biggest, give the molecules present on the cell membrane.
phospholipids, sterol lipids, proteins
What are the 7 membrane functions?
- define cell
- selective transport
- enzyme activity
- signal transduction - proteins receptors
- cell adhesion - celle to cell links
- cell recognition
- attachment to cytoskeleton
Why can the function of cell variate from one to an other?
Because of the proteins present on the membrane.
FOr what are proteins receptor used in the cell membrane?
To transfer a message from outside to inside of the cell. These proteins are often hormones.
When will one find more cell to cell links?
In organs that have to expand a lot .
What are the 3 names of passive tranport in cells?
- diffusion
- osmosis
- facilitated diffusion
What is diffusion?
It is the movement of particules down concentration gradient.
What is the gradient?
The “slope”. Down gradient means that it goes from high concentration to low concentration.
What molecules can diffuse through the membrane?
They are small and non-polar molecules.
H2O, O2, CO2, N2, hydrophobic molecules, lipid-soluble molecules
What is osmosis?
It is the pasive tranport of water through the molecule by aquporin channels. It goes from a hypotonic (low in salt) to a hypertonic (high in salt) environment until both environment are isotonic.
What are aquaporin channels?
They are protein imbeded in the membrane that allow water go trhough. They let more water molecule in than if there was only the bilayer.
What is an example of osmosis in plants?
Turgor pressure
What is an example of osmosis in everyday life?
using salts and sugars as preservative for food
What is an example of osmosis in animals?
Water moving into stomach after the addiction of HCL that transforms into ions in a aqueous solution.
What is an example of osmosis in protist?
Contractile vacuoles.
What is facilitated diffusion?
It is the transport of small solutes across the membrane down concentration gradient via specific transport proteins.
What are transport proteins?
They are channels³hole in the membrane that allow specific molecules to travel trhough the cell membrane in a passive way.
Give example of facilitated transporter.
- Glucose transporter : letting the glucose molecule go in and out of the cell
- getes ion channe;s in membranes of neurons that open and close when the ions are needed.
Active transport?
against concentration gradient and requires energy ATP
requires transmembrane proteins
ATP?
energy molecule that is a direct energy source
ion pump?
moves ions against concentration gradient
function of ion pump?
maintain membrane potential
help maintain osmotic pressure
3 examples of ion pumps.
Na+/K+ ion pump
Ca++pump in sarcoplasmic reticulum
proton pump
What is the Ca++ pump for?
The Ca++ is stored in specialized organelles.
Ca++ is low in muscle cells and high in organelles
membrane potential?
inside charge are negative and outside charges are positives
Proton pump?
transport H+ into
LYSOSOME : where digestion at cellular level happens
MITOCHONDRIA: where ATP is produced
co-transport?
2 ions move through the same transport molecule
- down concentration gradient
- against concentration gradient
examples of co-transport?
symport, antiport
symport?
coupled molecule moving in he same direction, 1 against one down concentration gradient in co-transport
antiport?
coupled molecule moving in opposite direction
symport vs antiport?
symport move in same direction, antiport move in opposite direction
clues for active transport?
2 molecules trhrough the same door
against concentration
use ATP
exocytosis?
secretion of macromolecules by vesicles with plasma membrane
vesicles?
ball of membrane where stuff can be stuffed inside
secretion?
moving out of the cell
what is the role of ATP in exocytosis?
it is used to move de vesicles
what happens with the vesicles nd the embrane?
They fuse together because they are the same bilayered phospholipid membrane
examples of exocytosis (5)
- neuron secretion of neurotransmitters
- secretion of hormones and enzymes by glandular cells
- insertion of plasma membrane
- insertion of transmembrane proteins and external surface proteins
- antigen presentation - immune response
endocytosis - what?
uptake macromolecules from outside the cell to bring them inside the cell within a vesicle
endocytosis - types
- phagocytosis
- pinocytosis
- receptor-mediated endocytosis
phagocytosis - what?
endocytosis that creates food vacuoles
DRAWING
phagocytosis - examples
white blood cells engulf /surrounds invading bacterial cells
pinocytosis - what?
endocytosis that uptakes extracellular fluids (with dissolves solutes in it)
UNSPECIFIC DRAWIND
pinocytosis - example
kidney cells use it to absorb proteins from urine
pinocytosis - membane
the vesicles forms from the cell membrane
receptor-mediated endocytosis - what?
intake particules with receptor proteins within the membrane (inner and outer surface)
the membrane can not make the vesicul on its own, it needs the receptor proteins DRAWING
receptor-mediated endocytosis - examples
uptaking of cholesterol
